Lake becoming ‘unfishable’
An experienced fishing guide fears Lake Wakatipu could end up ‘‘unfishable’’ with the invasive spread of the algae bloom, lake snow, and warns Lake Dunstan could be next.
Queenstown fishing guide Stu Dever, armed with his rod and reel, voiced his concerns about the presence of lake snow in Lake Wakatipu to Otago Fish and Game committee members at a meeting in Cromwell on Thursday.
His rod was clogged with the thick globules of algae after only one day’s fishing on the lake.
‘‘That rod, I only used once for one fishing trip and got that buildup from lake snow - the problem is very bad. It has got to the stage if you don’t clean your reel you can’t wind it in it gets that thick.’’
The mucous-like substance produced by the algae cyclotella has now been observed in three South Island lakes. In May, slime taken from Lake Wakatipu was confirmed as lake snow. The algae was also found on a fishing line at Lake Coleridge in 2015, after initially being discovered in Lake Wanaka in 2004.
Dever said he first noticed the thick globules of algae in Lake Wakatipu in April and it had got progressively worse.
‘‘It is on the top but it’s also down deep and right through vari- ous levels. I have no idea how it got into the lake but if nothing is done about it, I don’t know where it could end up. The lake could be totally unfishable.’’
He warned the spread would flow-on to Lake Dunstan, in Cromwell.
‘‘It will flow on to Lake Dunstan - our lake drains into Cromwell from the Kawarau River...Something has to be done now, urgently...
‘‘The algae also blocks boat filters and I understand our drinking water comes out of the lake and the algae is blocking the filters for the town’s water supplies. That is one of the major things for Wanaka, it gets into the irrigation pumps.’’
Otago Fish and Game operations manager Ian Hadland said lake snow was not a new issue with lake-users struggling with it in Wanaka, but it had not been prevalent in Lake Wakatipu up until this point.
‘‘It is a relatively new phenomenon there and it is the worst we have seen it at both.’’
It had not been noticed in Lake Dunstan but the Cromwell lake was at risk, he said.
An Otago University academic had been researching it.